Fuel compositions for vehicles are continually being improved to enhance various properties of the fuels in order to accommodate their use in newer, more advanced engines, such as in direct injected gasoline engines. Accordingly, fuel compositions typically include additives that are directed to certain properties that require improvement. For example, friction modifiers, such as fatty acid amides are added to fuel to reduce friction and wear in the fuel delivery systems of an engine. However, certain fatty acid amides may be unstable in additive packages for fuels at low storage temperatures and the performance of such fatty acid amides is less than desirable. Fuel additives may be passed into the oil sump during engine operation, so that a fuel additive that is also beneficial to the engine lubricant is desirable. While such additives may be beneficially added to the lubricant rather than the fuel, such additives are not effective for improving wear in fuel delivery systems. Also, such additives, when added to the fuel, rather than the lubricant, may reduce friction and wear in the piston ring zone of the engine and thus improve fuel economy. Accordingly, it is significantly more advantageous to include additives to fuels rather than to lubricants which can provide both improved fuel delivery system wear protection as well as improved fuel economy.
Partial esters of fatty acid and polyhydroxy alcohols such as glycerol monooleate (GMO) are known as friction modifiers for lubricant compositions. While GMO may improve fuel economy when added to a lubricant, GMO is unstable in additive packages for fuels and is known to cause an increase in intake valve deposits in gasoline engines.
Many other friction modifiers have been tried, however there remains a need for a friction modifier that is relatively stable in fuel additive packages, that is resistant to hydrolysis, that may be readily formulated into a fuel additive packages, that offers acceptable fuel economy benefits, and that provides wear protection to fuel delivery systems, among others characteristics. Accordingly, there continues to be a need for a fuel additive that is cost effective to manufacture and improves multiple characteristics of a fuel.
In accordance with the disclosure, exemplary embodiments provide a fuel composition and method for reducing wear and improving fuel economy in an engine. The fuel composition includes gasoline and from about 10 to about 750 ppm by weight based on a total weight of the fuel composition of a hydroxyalkyl hydrocarbyl-substituted succinimide compound having at least two hydroxyl groups attached to a tertiary nitrogen atom of a polyamino group through a hydrocarbyl link, wherein the hydroxyalkyl hydrocarbyl-substituted succinimide is devoid of primary and secondary amino groups.
In one embodiment of the disclosure, there is provided fuel composition for reducing friction or wear and improving engine fuel economy. The fuel composition includes gasoline and from about 10 to about 750 ppm by weight based on a total weight of the fuel composition of a reaction product that is derived from a hydrocarbyl-substituted succinic anhydride, a hydrocarbyl-substituted succinic ester, or hydrocarbyl-substituted succinic acid and a polyamine that is subsequently reacted with an epoxide compound. The reaction product is devoid of primary and secondary amino groups.
In another embodiment, there is provided a method for reducing friction or wear and improving fuel economy in an engine. The method includes fueling the engine with a fuel composition containing gasoline and from about 10 to about 750 ppm by weight based on a total weight of the fuel composition of a hydroxyalkyl hydrocarbyl-substituted succinimide compound having at least two hydroxyl groups attached to a tertiary nitrogen atom of a polyamino group through a hydrocarbyl link, wherein the hydroxyalkyl hydrocarbyl-substituted succinimide is devoid of primary and secondary amino groups, and operating the engine on the fuel composition.
An advantage of the fuel compositions and methods described herein is that the additive for the fuel composition may not only improve the friction or wear properties in an engine and fuel delivery system, but the additive may also be effective to improve fuel economy. An advantage of the hydroxyalkyl hydrocarbyl-substituted succinimide compound described above in a fuel additive package is that the additive package remains in a liquid state even at a temperature as low as −20° C. so that the entire additive package remains dissolved or suspended in the fuel composition. Another advantage of the hydroxyalkyl hydrocarbyl-substituted succinimide compound is that it is devoid of primary and secondary amino groups thereby improving the seal compatibility and demulsibility of fuel containing the reaction product.
In a further embodiment, the fuel composition contains from about 10 to about 750 ppm by weight, such as from 20 to about 500 ppm by weight, or from 30 to about 250 ppm by weight of the hydroxyalkyl hydrocarbyl-substituted succinimide compound based on a total weight of the fuel composition.
In another embodiment, an oil of lubricating viscosity contains from 0.05 to 5.0 wt. %, such as from 0.1 to 1.0 wt. %, or 0.15 to 0.5 wt. % of hydroxyalkyl hydrocarbyl-substituted succinimide compound based on the total weight of the oil composition.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.